U.S. Pat. No. 2,995,166 is illustrative of one process for removing skins from nuts, wherein the nuts are heated to loosen and crack the skins, followed by the use of air to blow the skins from the nuts. The nuts are trapped between a pair of porous moving belts, and air jets below the lower belt directed at the nuts causes the skin to be removed. The purpose of the upper belt is to hold the nuts on the lower belt against the air jet streams. The process of this patent is primarily for peanuts.
It is known to direct air jets downwardly onto a bed of nuts to dislodge the skins, collecting the skins in a cyclone or similar collection device through which the skins and treating air are passed. In the treatment of almonds, this step is preceded by a soaking step wherein the nuts are soaked in water or sodium hydroxide for about 8 hours. Washing removes all but about 5-10% of the skins. Subsequently, the nuts are then dried in a conveyor dryer to remove moisture from the nuts, the air jet apparatus of above being a part of this dryer, for the purpose of removing the remaining 5-10% of the skins.
A principal problem with this process is that the bed depth, because the air jets are directed downwardly, is limited to about 1 inch or so, limiting the capacity which the dryer can handle. This in turn adds unduly to the cost of the drying and skin removal operation. The problem is particularly evident with the removal of skins from almonds, due to the size, shape and density of these almonds, and generally tight adherence of the skins to the nut surfaces.